A note on the occurrence of non-symbiotic nitrogen-fixing bacteria in some introduced-pasture soils

Summary

Azotobacter species were not detected in five soils, of medium natural fertility, which were originally under forest but which had been under introduced-grass pastures for several years.

Counts were made of Clostridium butyricum in two of these soils under grass and clover pastures. The numbers of these anaerobic bacteria were low and the amounts of nitrogen fixed by them in pastures would be very small compared with those fixed by the clover-Rhizobium association.